Tapping on powder paint does take a little practice to get it looking good. I don't know that the brush matters as much as just generally how hard you tap. As long as the brush hold some powder, you should be good. As i mentioned about the force you use to tap, a trick i have learned is that the first tap or 2 should be harder and just tapped back over top of the paint jar. A whole lot of powder will come off the brush on those first taps and can really thicken it up and change colors quick. After you get the excess off, you should get a lighter powder coming off the brush. This is definitely helpful if you are trying to get a smooth color change or if you just want a light coat.
Also for colors...... i always try to work light to dark. That is just a general art logic though, don't always have to follow the rules, but it can make life easier in some situations.
Glad to see you post!